基于分层模型预测控制的风电场电压协调控制策略

针对弱连接并网风电场无功电压调节中电压支撑能力较弱且易受风功率波动影响的问题,提出一种基于多时间级垂直分层思想与模型预测控制(MPC)理论相结合的风电场无功电压分层协调控制策略。首先,在自适应调节层,依据风电场调节能力与并网点电压波动轨迹预测,提出一种并网点电压自适应调节策略。其次,在无功分配层,求解无功需求容量,并给出一种可考虑各机组无功调节裕度的改进比例分配策略。最后,在跟踪控制层,依据状态预测与参考、反馈信息实时修正控制误差。通过分层MPC,各层内不同时间级的预测信息可被高效利用,各层间不同时间尺度的控制亦可得到有效协调。基于PSCAD的仿真分析结果验证了所提方法的有效性。

Coordinated Voltage Control Strategy of Wind Farms Based on Hierarchical Model Predictive Control

The voltage of point of common coupling(PCC)is susceptible to the random fluctuation of wind power when the grid at the connection point is weak. A hierarchical and coordinated control strategy for reactive power and voltage of wind farms is proposed based on the combination of multiple time scale vertical hierarchical thought and model predictive control(MPC)theory. Firstly, in the adaptive adjustment layer, an adaptive voltage regulation strategy is proposed according to the reactive power capability of the wind farm and the voltage prediction track at PCC. Secondly, in the reactive power distribution layer, the reactive power demand capacity is optimized, and an improved proportional allocation strategy that considers the reactive power margin of each generator is proposed. Finally, in the tracking control layer, the control error is corrected in real time according to the state prediction and reference as well as feedback information. Through hierarchical MPC, the prediction information of different time scales in each layer can be fully utilized, and the control between different layers can be coordinated effectively. The simulation results based on PSCAD verify the effectiveness of the proposed method. This work is supported by National Natural Science Foundation of China(No. 51607107), Fundamental Research Funds of Shandong University(No. 2018JC029)and State Grid Corporation of China(No. 52060018000X).